The overall objective of the proposed research is to provide an experimental analysis of the effects of cocaine on sensory and motor function in non-human primates. Animal psychophysical procedures will be employed to obtain quantitative assessments of the effects of cocaine on the following aspects of sensory function: 1) absolute auditory thresholds; 2) absolute visual thresholds; 3) the discrimination of auditory frequency differences; and 4) discrimination of synthetic speech sounds. For each of these aspects of sensory function, motor function will also be assessed by examining reaction times to each type of sensory stimulus employed. All experiments will be conducted using a standard reaction time procedure with non-restrained laboratory baboons. The proposed research will assess the effects of both acute and chronic cocaine dosing regimens on sensory/motor function, and will also examine the effects of doses of cocaine combined with other drugs of abuse (ethanol, delta-9-THC, pentobarbital). The results will provide basic data on the effects of cocaine on sensory and motor function across a range of drug doses, and on the interaction effects of cocaine with other common drugs of abuse. The study will also provide information relevant to drug scheduling and clinical evaluation of functional decrements produced by cocaine.